1. Field of the Invention
The present invention relates to a motor control apparatus and a motor control method and, more specifically, it relates to a technology whereby a higher harmonic current flowing through a 3-phase AC motor is reduced.
2. Description of the Related Art
The applicant of the present invention proposed a motor control apparatus that reduces a higher harmonic current flowing through a 3-phase AC motor in Japanese Patent Application No. 2000-356117. The motor control apparatus, which includes a fundamental current control circuit that controls a fundamental current in a dq-axis coordinate system rotating in synchronization with the motor rotation and a higher harmonic current control circuit that controls a higher harmonic current in a dhqh coordinate system rotating at a frequency set to an integral multiple of the frequency of the fundamental current, controls a current flowing to the 3-phase AC motor. The fundamental current control circuit calculates a d-axis voltage command value and a q-axis voltage command value to be used to match the actual d-axis current and q-axis current with their command values, whereas the higher harmonic current control circuit calculates a dh-axis voltage command value and a qh-axis voltage command value to be used to match the actual dh-axis current and qh-axis current with their command values. Then, the d-axis and q-axis voltage command values and the dh-axis and qh-axis voltage command values are added together to convert them to 3-phase AC voltage command values, and the AC voltages thus determined are applied to the 3-phase AC motor through an invertor.